The mathematical problem of studying the behavior (e.g., velocities, positions)
of any number of objects moving under their mutual gravitational attraction for
any time in the past or future. Same as the → many-body problem.

The largest and the most luminous → H II region in the
→ Small Magellanic Cloud, which contains the prominent
OB star cluster → NGC 346. N66 has a diameter of about
7 arcmin on the sky corresponding to about 120 pc for a distance of about
60 kpc. Compared with the → Orion Nebula, N66 has an Hα
luminosity almost 60 times higher.

Serial number in the Henize (1956) catalog, more precisely designated as
LHA 115-N66.

1) A small metal spike with a broadened flat head, driven into wood to join
things together or to serve as a hook.
2) A horny covering on the upper surface of the tip of the finger and toe in humans
and other primates (OxfordDictionaries.com).

A star visible without a telescope. In
principle, stars down to about sixth magnitude are visible to the
naked eye under ideal conditions, but this
depends on the individual, the location, and the conditions of the
observation.

The most stable carbon compound with an average particle size
of about 5 → nanometers (50 Å). Nanodiamonds
are synthesized by detonation of → T.N.T. and then
gathering the soot that remains from the explosion.